In the above-identified earlier applications, it is disclosed that mono-esters of a twelve carbon atom aliphatic fatty acid and a polyol unexpectedly provide effective non-toxic microbecides. For example, the ester may be the lauric acid ester of glycerol or other polyol and the esterification taking place with a single hydroxy group. The ester cannot be the di-ester, or tri-ester. As noted in the parent applications, this result is quite unexpected, since the art, as cited in the earlier applications, indicates that activity of that nature should not be expected. This is based on the evidence in the art that substantial microbecidal activity is occasioned only with lower-chain fatty acids, i.e., below twelve carbon atoms, and that some derivatives of the acids reduce the microbecidal activity thereof. Experimental data has shown that when fatty acids are converted into surface-active compounds, only the ionic derivatives are active and the non-ionic derivatives are not only inactive but will inactivate other microbecides in the composition.
The invention of the parent applications was, in part, the discovery that the microbecidal properties of fatty acids and their derivatives vary in a non-uniform manner with chain length and that the results obtained with parent acids are not necessarily translatable to the derivatives of those acids. It was determined that only the defined polyol mono-esters of a twelve-carbon atom acid function most effectively as food-grade microbecides and that compositions with high amounts of these esters can be compounded and remain non-toxic.
Additionally, as the earlier applications point out, an important feature is that the defined esters are dissolvable or dispersible in an aqueous medium. Of course, that function is extremely important in food compositions, since these compositions very often are water-based systems.
Conventional food-grade "phenolic" microbecides, such as butylated hydroxy anisole (normally referred to as BHA), and 2,6-di-tert-butyl-4-methyl phenol (commonly referred to as BHT) are important additives for foods and food-grade materials. These compounds are also important antioxidants, but since their microbecidal properties are particularly considered herein, they will be referred to hereinafter as simply microbecides, for the sake of simplicity. The "phenolic" compounds are not substantially water-dispersible (they are lipophilic) and are normally applied in food compositions via a lipid base or vehicle. This requirement considerably complicates the application of those conventional food-grade microbecides to food compositions. Unfortunately, if BHA and BHT are compounded with non-ionic surfactants (which are hydrophilic), in order to aid dispersibility in water systems, the surfactants substantially inactivate those compounds.
Accordingly, the esters of the earlier applicantions provide a distinct advantage, as opposed to the more usual food-grade microbecides, such as BHA and BHT, in that they are water-dispersible and are more easily incorporated into aqueous food systems. It would be, however, of a substantial advantage in the art if those conventional phenolic microbecides could be compounded with a non-ionic surface-active agent to aid in the water-dispersibility and without significantly decreasing the activity of those microbecides. This would allow a more convenient application of the microbecides in both food-grade applications and non-food-grade applications.